Research Projects

Ti alloys show a unique combination of lightweight and strength, among which the Ti-6wt.%Al-4wt.%V (Ti64) system is most abundantly used due to better fracture toughness, corrosion resistance, and bio-compatibility. Through the conventional casting route, development of Ti alloys with addition of higher amount of β stabilizing elements is difficult because of the casting-related issues like segregation, heterogeneity in microstructure etc. These issues can be addressed through additive manufacturing techniques, among which the direct energy deposition (DED) technique has added advantages with respect to part repairing and flexibility in alloy design. Through the DED process, we can explore a wider alloy space in different Ti alloy systems. A better homogeneity in microstructure, even for a high amount of alloying can be achieved through the DED process, because of the associated small instantaneous melt pool formation. Compositionally graded material can be developed through the use of multiple powder feeders, and varied powder flow rates. Development of Ti alloys through DED process needs strict environment control during operation in the machine. Less availability of such environment-controlled multi-feeder DED set up has caused limited research in exploring new alloy spaces in Ti-based systems. There is a huge scope for developing new Ti alloys with very attractive combinations of strength, ductility, and other mechanical properties for applications in the aerospace, automobile, and biomedical sectors. It has been observed that the limited addition of Fe (≤4 wt.%) to Ti64 helps in obtaining equiaxed microstructure as opposed to undesirable columnar structure and enhances strength of Ti64 alloy to a great extent. The addition of Cu to the Ti system has been found to create a large constitutional supercooling zone, which helps in improving both the strength and ductility (even at higher temperatures) of the Ti alloys through further grain refinement. The proven anti-bacterial property of Cu makes it a potential alloying element to the Ti64 system for various bio-implants too. Nb is another attractive β-phase stabilizer for bio-implant application; it also facilitates refined equiaxed grain formation. The improved mechanical properties and excellent bio-compatibility with Nb addition to Ti need more detailed study via DED route. Studies via the conventional route reported that adding Co to the Ti-Fe-based systems significantly enhances the ductility and wear properties. The present project aims to explore newer alloy spaces in different Ti alloy systems (Ti64-Fe-Cu, Ti64-Fe-Nb, and Ti64-Fe-Co systems) based on Ti64-Fe with alloying additions of Cu, Nb, and Co. It will involve DED process parameter optimization (to achieve, sound, homogeneous, and equiaxed microstructure), alloy development (with a wide range of compositions), and study of phase stability, bio-compatibility, along with assessment of mechanical and electro-chemical properties.